When using the Update Item action for a SharePoint List, it is not currently possible to clear a value that has been previously set in a Person or Group type field (Claims). Attempting to do this currently causes the Flow to fail, with a "Badgateway" 402 error, arising from a "user does not exist" 400 error. Please enable the dynamic content expression to allow use of the Null() function to clear previous content from ANY field type, including person or group claims fields.
... View more

There is no way to clear a field of type person or group. When trying to set it to empty it repsonds with cannot find user (or similar). Idea: For example if I set the field to the expression null the field should be emptied. Note! this could/should be implemented on all field types.
... View more